The Relationship between Population Structure and Aluminum Tolerance in Cultivated Sorghum

Background: Acid soils comprise up to 50% of the world's arable lands and in these areas aluminum (Al) toxicity impairs root growth, strongly limiting crop yield. Food security is thereby compromised in many developing countries located in tropical and subtropical regions worldwide. In sorghum, SbMATE, an Al-activated citrate transporter, underlies the Alt(SB) locus on chromosome 3 and confers Al tolerance via Al-activated root citrate release. Methodology: Population structure was studied in 254 sorghum accessions representative of the diversity present in cultivated sorghums. Al tolerance was assessed as the degree of root growth inhibition in nutrient solution containing Al. A genetic analysis based on markers flanking Alt(SB) and SbMATE expression was undertaken to assess a possible role for Alt(SB) in Al tolerant accessions. In addition, the mode of gene action was estimated concerning the Al tolerance trait. Comparisons between models that include population structure were applied to assess the importance of each subpopulation to Al tolerance. Conclusion/Significance: Six subpopulations were revealed featuring specific racial and geographic origins. Al tolerance was found to be rather rare and present primarily in guinea and to lesser extent in caudatum subpopulations. Alt(SB) was found to play a role in Al tolerance in most of the Al tolerant accessions. A striking variation was observed in the mode of gene action for the Al tolerance trait, which ranged from almost complete recessivity to near complete dominance, with a higher frequency of partially recessive sources of Al tolerance. A possible interpretation of our results concerning the origin and evolution of Al tolerance in cultivated sorghum is discussed. This study demonstrates the importance of deeply exploring the crop diversity reservoir both for a comprehensive view of the dynamics underlying the distribution and function of Al tolerance genes and to design efficient molecular breeding strategies aimed at enhancing Al tolerance.CGIAR[G3007.04]McKnight FoundationFundacao de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG)National Council for Scientific and Technological Development (CNPq

Speech Communication

Contains table of contents for Part V, table of contents for Section 1, reports on six research projects and a list of publications.C.J. Lebel FellowshipDennis Klatt Memorial FundNational Institutes of Health Grant R01-DC00075National Institutes of Health Grant R01-DC01291National Institutes of Health Grant R01-DC01925National Institutes of Health Grant R01-DC02125National Institutes of Health Grant R01-DC02978National Institutes of Health Grant R01-DC03007National Institutes of Health Grant R29-DC02525National Institutes of Health Grant F32-DC00194National Institutes of Health Grant F32-DC00205National Institutes of Health Grant T32-DC00038National Science Foundation Grant IRI 89-05249National Science Foundation Grant IRI 93-14967National Science Foundation Grant INT 94-2114

Genome sequence of white lupin, a model to study root developmental adaptations.

International audienc

Genome Sequence Of White Lupin, A Model To Study Root Developmental Adaptations

International audienc

Anatomical and hormonal description of rootlet primordium development along white lupin cluster root.

Cluster root (CR) is one of the most spectacular plant developmental adaptations to hostile environment. It can be found in a few species from a dozen botanical families, including white lupin (Lupinus albus) in the Fabaceae family. These amazing structures are produced in phosphate-deprived conditions and are made of hundreds of short roots also known as rootlets. White lupin is the only crop bearing CRs and is considered as the model species for CR studies. However, little information is available on CRs atypical development, including the molecular events that trigger their formation. To provide insights on CR formation, we performed an anatomical and cellular description of rootlet development in white lupin. Starting with a classic histological approach, we described rootlet primordium development and defined 8 developmental stages from rootlet initiation to their emergence. Due to the major role of hormones in the developmental program of root system, we next focussed on auxin-related mechanisms. We observed the establishment of an auxin maximum through rootlet development in transgenic roots expressing the DR5:GUS auxin reporter. Expression analysis of the main auxin related genes (TIR, ARF, AUX/IAA…) during a detailed time course revealed specific expression associated with the formation of the rootlet primordium. We showed that LaTIR1b [TRANSPORT INHIBITOR RESPONSE 1b] is expressed during rootlet primordium formation and that LaARF5 [AUXIN RESPONSE FACTOR 5] is expressed in the vasculature but absent in the primordium itself. Altogether, our results describe the very early cellular events leading to CR formation and reveal some of the auxin-related mechanisms

Genome sequence of white lupin, a model to study root developmental adaptations

White lupin ( Lupinus albus ; 2n=50) stands out as a model legume species since it is the only crop producing cluster roots, one of the most outstanding developmental adaptations to nutrient‐scarce environments. We report a high‐quality chromosome‐scale assembly of white lupin genome, together with an extensive transcriptome data from ten different organs of that species. We took advantage of single‐molecule real‐time technology, in combination with short‐reads sequencing and optical and genetic maps in order to have a successful assembly. The final assembly size is 451Mb with a N50 of 17Mb. About 96% (434Mb) of the assembled genome is included on the 25 pseudo‐chromosomes. The structural annotation identified 38 258 coding genes and 3129 ncRNA, being 97.3% genes anchored on the pseudo‐chromosomes. A majority (94.6%) of the 1440 genes in the Plantae BUSCO dataset were identified in the annotation, which is suggestive of a complete assembly and annotation. White lupin genome revealed to be laden with gene duplications and repetitive elements. It presents extensive duplication blocks inside its own genome and also a high degree of synteny with the close legumes species Lupinus angustifolious and Medicago truncatula . This genome is a valuable resource and represents a keystone for legumes genomics research

Genome sequence of white lupin, a model to study root developmental adaptations

White lupin ( Lupinus albus ; 2n=50) stands out as a model legume species since it is the only crop producing cluster roots, one of the most outstanding developmental adaptations to nutrient‐scarce environments. We report a high‐quality chromosome‐scale assembly of white lupin genome, together with an extensive transcriptome data from ten different organs of that species. We took advantage of single‐molecule real‐time technology, in combination with short‐reads sequencing and optical and genetic maps in order to have a successful assembly. The final assembly size is 451Mb with a N50 of 17Mb. About 96% (434Mb) of the assembled genome is included on the 25 pseudo‐chromosomes. The structural annotation identified 38 258 coding genes and 3129 ncRNA, being 97.3% genes anchored on the pseudo‐chromosomes. A majority (94.6%) of the 1440 genes in the Plantae BUSCO dataset were identified in the annotation, which is suggestive of a complete assembly and annotation. White lupin genome revealed to be laden with gene duplications and repetitive elements. It presents extensive duplication blocks inside its own genome and also a high degree of synteny with the close legumes species Lupinus angustifolious and Medicago truncatula . This genome is a valuable resource and represents a keystone for legumes genomics research

Relative contribution of plant traits and soil properties to the functioning of a temperate forest ecosystem in the Indian Himalayas

© 2020 Elsevier B.V. Plant-soil interactions are a major determinant of changes in forest ecosystem processes and functioning. We conducted a trait-based study to quantify the contribution of plant traits and soil properties to above- and below-ground ecosystem properties in temperate forest in the Indian Himalayas. Nine plant traits (leaf area, specific leaf area, leaf water content, leaf dry matter content, leaf carbon (C), nitrogen (N), phosphorus (P), leaf C/N, and leaf N/P) and eight soil properties (pH, moisture, available N, P, potassium (K), total C, N, P) were selected for determination of their contribution to major ecosystem processes (above-ground biomass C, soil organic C, soil microbial C, soil microbial N, soil microbial P, and soil respiration) in temperate forest. Among the plant traits leaf C, N, P, and leaf N/P ratio proved to be the main contributors to above-ground biomass, explaining 20–27% of variation. Leaf N, P, and leaf N/P were the main contributors to below-ground soil organic C, soil microbial C, soil microbial N, soil microbial P, and soil respiration (explaining 33% of variation). Together, the soil properties, pH, available P, total N and C explained 60% of variation in above-ground biomass, while pH and total C explained 56% of variation in soil organic C. Other soil properties (available P, total C and N) also explained much of the variation in soil microbial C (52%) and soil microbial N (67%), while soil pH explained some of variation in soil microbial N (14%). Available P, total N, and pH explained soil microbial P (81%), while soil respiration was only explained by soil total C (70%). Thus, leaf traits and soil characteristics significantly explaining variations in above- and below-ground ecosystem processes and functioning in temperate forest in the Indian Himalayas. Consequently, tree species for afforestation, restoration, and commercial forestry should be carefully selected, as they can influence the climate change mitigation potential of forest in terms of C stocks in biomass and soils.The authors thank the Uttrakhand Forest Department for permission to use the study site. MR was supported by an INSPIRE Fellowship from the Department of Science and Technology (DST), Government of India. JMA was supported by Qatar Petroleum

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