Canopy Temperature Depression as an Effective Physiological Trait for Drought Screening

Water stress is a major production constraint in agriculture worldwide. Efforts to breed for drought tolerance are invariably hampered by the amount of time required to phenotype a large number of individuals and poor or inconsistent correlations and multiple mechanisms involved. Canopy temperature depression has emerged as a potential surrogate in view of substantial natural variation in crops as well as its correlation with yield. Based on the experimental findings two types of ideotype models based on CTD have been proposed as isohydric (“water saving”) and anisohydric (“water spending”). The isohydrics have advantage in the harsher environments, whereas the anisohydrics perform better under moderate/mild drought situations. Water savers have a shallow root system with intermediate root growth and thin roots. They are early and have high water use efficiency, reduced transpiration and limited leaf area and canopy biomass development and superior photosynthate remobilization to pod and grain. Contrary to this, water spenders have a vigorous and deep rooting system with rapid root growth and a thicker root system. Such genotypes are early and have highly effective water use, moderate transpiration and fast leaf area and canopy biomass development, moderate sink strength and superior photosynthate remobilization to pod and grain formation

Reactive Oxygen Species, Oxidative Damage and Their Production, Detection in Common Bean (<em>Phaseolus vulgaris</em> L.) under Water Stress Conditions

Reactive oxygen species (ROS) being small and highly reactive oxygen containing molecules play significant role in intracellular signaling and regulation. Various environmental stresses lead to excessive production of ROS causing progressive oxidative damage and ultimately cell death. This increased ROS production is, however, tightly controlled by a versatile and cooperative antioxidant system that modulates intracellular ROS concentration and controls the cell’s redox status. Furthermore, ROS enhancement under stress serves as an alarm signal, triggering acclimatory/defense responses via specific signal transduction pathways involving H2O2 as a secondary messenger. Nevertheless, if water stress is prolonged over to a certain extent, ROS production will overwhelm the scavenging action of the anti-oxidant system resulting in extensive cellular damage and death. DAB (3,3′-diaminobenzidine) test serves as an effective assessment of oxidative damage under stress. It clearly differentiates the lines on the basis of darker staining of leaves under water stress. The lines showing greater per cent reduction in yield parameters show greater staining in DAB assay underlining the reliability of using this assay as a reliable supplement to phenotyping protocols for characterizing large germplasm sets

Genetic architecture for yield and its components in maize (Zea mays L)

Fifteen phenotypically diverse inbred lines were crossed to three testers diverse testers namely W3, W5 and their F1 W3 x W5 in a triple test cross fashion. The parental lines and test crosses were evaluated along with two standard checks C15 and W3 x W8 during kharif 2005 in a randomised complete block design at two diverse locations of Kashmir valley viz., High Altitude Rice Research Sub-station Larnoo and Regional Research Station and Faculty of Agriculture Wadura, with three replications at each location. Observations were taken for 14 quantitative traits and were subjected to statistical analysis as proposed by Kearsey and Jinks (1968). The analysis of variance revealed significant mean squares due to progenies, lines, testers crosses and parents v/s crosses in most of the traits except prolificacy index indicating wide variability in the material used and that parents and crosses were significantly different from each other in their performance. The environmental component and G x E interaction was significant for most of the traits indicating strong influence of environment on these traits. The analysis of variance for detection of epistasis revealed that epistasis was significant for most of the traits except number of ears plot-1, and harvest index. The partitioning of epistasis into its fixable [i] and non-fixable [j + l] components revealed significance of both the components except in case of days to pollen shed, days to 75 per cent husk browning and 100-grain weight for which [i] type epistasis was non-significant. In most cases non-additive interaction component [j+l] was greater in magnitude than its corresponding [i] type epistasis. For most of the traits, the expression of epistasis and its components was affected by environmental variations. The analysis of genetic components of variance showed significance of both additive and dominance gene effects with preponderance of additive component for most of the traits except prolificacy index for which only dominance effects were significant. The results imply that simple selection strategies can bring about substantial improvement for these traits. In the present study standard heterosis was estimated using C15 and W3 x W8 as checks. The heterosis estimates over C15 were substantial as compared to W3 x W8, where heterotic effects were not encouraging for most of the traits including grain yield except maturity traits for which substantial heterosis upto –16.21 per cent was recorded in the cross CML-79 x W5. For grain yield heterosis upto 10.64 per cent was exhibited by cross CML-173 x W5 over C15. The degree of dominance was in the range of partial dominance for all traits. The direction of dominance was positive or negative but non-significant indicating ambi-directional nature of dominance. Correlation (sums/differences) was also non-significant for all traits except 100-grain weight. The implications of the findings of present study on maize breeding have been discussed in light of available literature

Metabolic-GWAS provides insights into genetic architecture of seed metabolome in buckwheat

Abstract Background Buckwheat (Fagopyrum spp.), belonging to the Polygonaceae family, is an ancient pseudo-cereal with high nutritional and nutraceutical properties. Buckwheat proteins are gluten-free and show balanced amino acid and micronutrient profiles, with higher content of health-promoting bioactive flavonoids that make it a golden crop of the future. Plant metabolome is increasingly gaining importance as a crucial component to understand the connection between plant physiology and environment and as a potential link between the genome and phenome. However, the genetic architecture governing the metabolome and thus, the phenome is not well understood. Here, we aim to obtain a deeper insight into the genetic architecture of seed metabolome in buckwheat by integrating high throughput metabolomics and genotyping-by-sequencing applying an array of bioinformatics tools for data analysis. Results High throughput metabolomic analysis identified 24 metabolites in seed endosperm of 130 diverse buckwheat genotypes. The genotyping-by-sequencing (GBS) of these genotypes revealed 3,728,028 SNPs. The Genome Association and Prediction Integrated Tool (GAPIT) assisted in the identification of 27 SNPs/QTLs linked to 18 metabolites. Candidate genes were identified near 100 Kb of QTLs, providing insights into several metabolic and biosynthetic pathways. Conclusions We established the metabolome inventory of 130 germplasm lines of buckwheat, identified QTLs through marker trait association and positions of potential candidate genes. This will pave the way for future dissection of complex economic traits in buckwheat

Morpho-Cultural and Pathogenic Variability of <i>Sclerotinia sclerotiorum</i> Causing White Mold of Common Beans in Temperate Climate

The present systematic research on cultural, morphological, and pathogenic variability was carried out on eighty isolates of Sclerotinia sclerotiorum collected from major common bean production belts of North Kashmir. The isolates were found to vary in both cultural and morphological characteristics such as colony color and type, colony diameter, number of days for sclerotia initiation, sclerotia number per plate, sclerotial weight, and size. The colony color ranged between white and off-white with the majority. The colony was of three types, in majority smooth, some fluffy, and a few fluffy-at-center-only. Colony diameter ranged between 15.33 mm and 29 mm after 24 h of incubation. The isolates took 4 to 7 days for initiation of sclerotia and varied in size, weight, and number per plate ranging between 14 and 51.3. The sclerotial arrangement pattern on plates was peripheral, sub peripheral, peripheral, and subperipheral, arranged at the rim and scattered. A total of 22 Mycelial compatibility groups (MCGs) were formed with seven groups constituted by a single isolate. The isolates within MCGs were mostly at par with each other. The six isolates representing six MCGs showed variability in pathogenicity with isolate G04 as the most and B01 as the least virulent. The colony diameter and disease scores were positively correlated. Sclerotia were observed to germinate both myceliogenically and carpogenically under natural temperate conditions of Kashmir. Germplasm screening revealed a single resistant line and eleven partially resistant lines against most virulent isolates

Explicating genetic architecture governing nutritional quality in pigmented rice

Rice is one of the most important staple plant foods that provide a major source of calories and nutrients for tackling the global hunger index especially in developing countries. In terms of nutritional profile, pigmented rice grains are favoured for their nutritional and health benefits. The pigmented rice varieties are rich sources of flavonoids, anthocyanin and proanthocyanidin that can be readily incorporated into diets to help address various lifestyle diseases. However, the cultivation of pigmented rice is limited due to low productivity and unfavourable cooking qualities. With the advances in genome sequencing, molecular breeding, gene expression analysis and multi-omics approaches, various attempts have been made to explore the genetic architecture of rice grain pigmentation. In this review, we have compiled the current state of knowledge of the genetic architecture and nutritional value of pigmentation in rice based upon the available experimental evidence. Future research areas that can help to deepen our understanding and help in harnessing the economic and health benefits of pigmented rice are also explored

Delineating Marker-trait Associations for Fusarium Wilt in Chickpea using Axiom® Cicer SNP Array

Fusarium wilt (FW) caused by the Fusarium oxysporum f. sp. ciceri is a devastating disease of chickpea (Cicer arietinum L.). To identify promising resistant genotypes and genomic loci for FW resistance, a core set of 179 genotypes of chickpea was tested for FW reactions at seedling and reproductive stages under field as well as controlled conditions in the greenhouse. Our results revealed that at seedling stage, most of the genotypes were found resistant whereas, at the reproductive stage majority of the genotypes were found susceptible. Genotyping using a 50K Axiom®Cicer SNP Array and trait data of FW together led to the identification of 26 significant (p≤E-05) marker-trait associations (MTAs) for FW resistance. Among 26 MTAs, 12 were identified using trait data recorded in the field (3 at seedling and 9 at reproductive stage) and 14 MTAs were identified using trait data recorded under controlled conditions in the greenhouse (6 at seedling and 8 at reproductive stage). The phenotypic variation explained by these MTAs varied from 11.75 to 15.86% with an average of 13.77%. Five MTAs were classified as major, explaining more than 15% phenotypic variation for FW and two MTAs were declared stable, being identified in either two environments or at two growth stages. One of the promising stable and major MTAs (Affx_123280060) detected in field conditions at reproductive stage was also detected in greenhouse conditions at seedling and reproductive stages. The stable and major (>15% PVE) MTAs can be used in chickpea breeding programmes