Biochemical mechanisms of resistance to shoot fly, atherigona soccata (rondani) in sorghum, sorghum bicolor (l.) Moench

Sorghum is the fifth major cereal crop after wheat, rice, corn, and barley, and third important cereal crop after rice and wheat in India. Nearly 150 insect species have been reported as pests on sorghum, of which sorghum shoot fly, Atherigona soccata, is an important pest. Host plant resistance is one of the important components for managing this pest, and therefore, the present studies were undertaken on biochemical mechanisms of resistance to shoot fly to strengthen host plant resistance to this insect for sustainable crop production. Genotypes IS 2312, SFCR 125, SFCR 151, ICSV 700, and IS 18551 exhibited antixenosis, antibiosis, and tolerance components of resistance to shoot fly, A. soccata. There was a significant variation in the leaf surface wetness, leaf glossiness, trichome density, seedling vigor, plumule and leaf sheath pigmentation, days to 50% flowering, and plant height among the test genotypes. Transplanting and clipping of sorghum seedlings reduced shoot fly damage. There was no effect of p-hydroxy benzoic acid (PHBA), p-hydroxy benzaldehyde (PHB), Cu2So4, KI, and 2, 4- D on shoot fly damage. However, application of PHBA showed increase in egg laying by the shoot fly females. Sorghum genotypes with high amounts of soluble sugars, more leaf surface wetness and fats, and better seedling vigor were susceptible to shoot fly; while those with glossy leaf trait, pigmented plumule and leaf sheath, tall with high trichome density; and high tannin, Mg, and Zn contents showed resistance to shoot fly. Leaf surface wetness, Mg, Zn, soluble sugars, tannins, fats, leaf glossiness, leaf sheath and plumule pigmentation, and trichome density explained 99.8% of the variation for deadhearts, of which leaf glossiness, plumule pigmentation, trichomes, and fat content had direct effects and correlation coefficients for iii deadhearts in the sam

Leaf surface chemistry of sorghum seedlings influencing expression of resistance to sorghum shoot fly, Atherigona soccata

Sorghum shoot fly, Atherigona soccata is one of the serious constraints to sorghum production, and host plant resistance is an important component for controlling this pest. We studied the expression of resistance to A. soccata in a diverse array of sorghum genotypes in relation to composition of leaf surface chemicals during the seedling stage. The sorghum genotypes IS 1054, IS 1057, IS 2146, IS 4664, IS 2312, IS 2205, SFCR 125, SFCR 151, ICSV 700, and IS 18551 exhibited antixenosis for oviposition, and suffered less deadhearts due to sorghum shoot fly, A. soccata. Compounds undecane 5- methyl, decane 4- methyl, hexane 2, 4- methyl, pentadecane 8- hexyl, and dodecane 2, 6, 11- trimethyl, present on the leaf surface of sorghum seedlings, were associated with susceptibility to shoot fly; while 4, 4- dimethyl cyclooctene was associated with resistance to shoot fly. The compounds associated with resistance/susceptibility to shoot fly, can be used as marker traits to select for resistance as well as for diversifying and increasing the levels of resistance to this pest. The role of biochemical compounds for developing sorghum varieties with resistance to shoot fly, A. soccata has been discussed

Physico-chemical mechanisms of resistance to shoot fly, Atherigona soccata in sorghum, Sorghum bicolor

Sorghum shoot fly, Atherigona soccata is an important pest of sorghum, and host plant resistance is one of the important components for minimizing the losses due to this pest. Therefore, we evaluated a diverse array of sorghum genotypes to identify physico-chemical characteristics conferring resistance to A. soccata. Susceptibility to shoot fly was associated with high amounts of soluble sugars, fats, leaf surface wetness and seedling vigour; while leaf glossiness, plumule and leaf sheath pigmentation, trichome density and high tannin, Mg and Zn showed resistance to shoot fly. Stepwise regression indicated that Mg, Zn, soluble sugars, tannins, fats, leaf glossiness, leaf sheath and plumule pigmentation and trichome density explained 99.8% of the variation in shoot fly damage. Path coefficient analysis suggested that leaf glossiness, trichome density, Mg and fat content and plant plumule pigmentation can be used as markers traits to select for shoot fly resistance in sorghu

Constitutive and Inducible Resistance to Atherigona soccata (Diptera: Muscidae) in Sorghum bicolor

Host plant resistance is one of the important components for minimizing the losses because of sorghum shoot fly, Atherigona soccata (Diptera: Muscidae) attack. Therefore, we studied the constitutive and inducible biochemical mechanisms of resistance to A. soccata in a diverse array of sorghum genotypes to identify lines with diverse mechanisms of resistance to this insect. Fifteen sorghum genotypes with different levels of resistance to A. soccata were evaluated. Methanol extracts of 10-d old damaged and undamaged sorghum seedlings were subjected to high-performance liquid chromatography analysis. Association between peak areas of the identified and unidentified compounds with parameters measuring A. soccata resistance was determined through correlation analysis. Amounts of p-hydroxy benzaldehyde and the unidentified compounds at RTs 24.38 and 3.70 min were associated with susceptibility to A. soccata. Genotypes exhibiting resistance to A. soccata were placed in four groups, and the lines showing constitutive and/ or induced resistance to A. soccata with different combinations of biochemical factors potentially could be used for increasing the levels of resistance to A. soccata in sorghum

Marker‐Assisted Backcrossing to Introgress Resistance to Fusarium Wilt Race 1 and Ascochyta Blight in C 214, an Elite Cultivar of Chickpea

Fusarium wilt (FW) and Ascochyta blight (AB) are two major constraints to chickpea (Cicer arietinum L.) production. Therefore, two parallel marker-assisted backcrossing (MABC) programs by targeting foc1 locus and two quantitative trait loci (QTL) regions, ABQTL-I and ABQTL-II, were undertaken to introgress resistance to FW and AB, respectively, in C 214, an elite cultivar of chickpea. In the case of FW, foreground selection (FGS) was conducted with six markers (TR19, TA194, TAA60, GA16, TA110, and TS82) linked to foc1 in the cross C 214 × WR 315 (FW-resistant). On the other hand, eight markers (TA194, TR58, TS82, GA16, SCY17, TA130, TA2, and GAA47) linked with ABQTL-I and ABQTL-II were used in the case of AB by deploying C 214 × ILC 3279 (AB-resistant) cross. Background selection (BGS) in both crosses was employed with evenly distributed 40 (C 214 × WR 315) to 43 (C 214 × ILC 3279) SSR markers in the chickpea genome to select plant(s) with higher recurrent parent genome (RPG) recovery. By using three backcrosses and three rounds of selfing, 22 BC3F4 lines were generated for C 214 × WR 315 cross and 14 MABC lines for C 214 × ILC 3279 cross. Phenotyping of these lines has identified three resistant lines (with 92.7–95.2% RPG) to race 1 of FW, and seven resistant lines (with 81.7–85.40% RPG) to AB that may be tested for yield and other agronomic traits under multilocation trials for possible release and cultivation

Translational Root Genomics for Crop Improvement

Breeding of crop plants in the 21st century needs consciousness and awareness of climate change. For instance, both biotic and abiotic stresses need attention of breeders in order to breed crops showing resistance/tolerance to these stresses in a changing climate scenario. In developing countries, drought is the major abiotic stress and is already limiting crop productivity in several species. This tendency is going to worsen the situation in the years to come (Varshney et al. 2011a). Enhancing crop productivity in resource-poor dry land conditions is a formidable challenge. Conserving resources through management practices and engineering plants for superior extraction of these resources coupled with an increased efficiency of resource utilization deserve emphasis. Though resource conservation through management practices are equally important, development of superior resource use efficiency as a seed-based technology always has greater acceptance and adaptability

Fast-track introgression of “QTL-hotspot” for root traits and other drought tolerance trait in JG 11, an elite and leading variety of chickpea (Cicer arietinum L.)

A “QTL-hotspot” containing QTLs for several root and drought tolerance traits was transferred through marker assisted backcrossing (MABC) into JG 11, a leading variety of chickpea in India from the donor parent ICC 4958. Foreground selection with up to 3 SSR (simple sequence repeat) markers namely TAA170, ICCM0249 and STMS11 and background selection with up to 10 AFLP (amplified fragment length polymorphism) primer combinations was undertaken. After undertaking three backcrosses with foreground and background selection and two rounds of selfing, 29 BC3F2 plants homozygous for two markers (ICCM0249 and TAA170) were selected and referred as introgression lines (ILs). Root trait phenotyping of these ILs showed higher rooting depth (RDp, average 115.21±2.24 cm) in all 29 ILs, better root length density (RLD, average 0.41±0.20 cm cm-3) in 25 ILs and higher root dry weight (RDW, average 1.25±0.08 g cyl-1) as compared to the recurrent parent, JG 11 (RDp- 111.70 cm, RLD- 0.39 cm cm-3 and RDW- 1.10 g cyl-1) as well as the donor parent, ICC 4958 (RDp- 114.20 cm, RLD- 0.45 cm cm-3 and RDW- 1.25 g cyl-1). These ILs, developed in 3 years, after multi-location field trials may be released as improved variety with enhanced drought tolerance

Genomic diversity among sorghum genotypes with resistance to sorghum shoot fly, Atherigona soccata

Host plant resistance is one of the important components for management of sorghum shoot fly, Atherigona soccata. The levels of resistance in cultivated germplasm are low to moderate, and therefore, it is important to identify sorghum genotypes with diverse mechanisms of resistance based on physico-chemical and or molecular markers. We assessed the genetic diversity of 15 sorghum genotypes with different levels of resistance/susceptibility to shoot fly, A. soccata using 93 sorghum simple sequence repeat (SSR) primer pairs and simultaneously characterized for 15 morpho-biochemical traits associated with shoot fly resistance

ANTIMICROBIAL AND ANTIOXIDANT ACTIVITY OF UREA/ THIOUREA DERIVATIVES OF 5-METHYL-3-(UREDIOMETHYL)-HEXANOIC ACID

A series of urea/ thiourea derivatives of 5-methyl-3-(urediomethyl)-hexanoic acid has been successfully synthesized from the reaction of 3-aminomethyl-5-methylhexanoic acid and aryl isocyanate/ aryl isothiocyanates in presence of triethylamine base in tetrahydrofuran solvent at rt-40C by stirring the contents for 3h