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Sheath blight of rice caused by Rhizoctonia solani Kuhn [teleomorph: Thanatephorus cucumeris (Frank) Donk] is a significant threat to rice cultivation, accounting for up to 50% yield losses. The present investigation demonstrates the early pathogenesis events and R. solani pre‐ and post‐penetration activities on moderately resistant (MR) and highly susceptible (HS) lines under field conditions. A pure culture of R. solani isolate (R1965) was inoculated inside the sheath at the maximum tillering stage for different time intervals (24, 48, 72 and 96 hpi). R. solani exhibited more profuse, dense, closely contact around surface grooves, lobate appressoria‐like structures and greater microsclerotia development on the HS line compared to the MR one. Using fluorescent, optical, and scanning electron microscopy, it was noticed for the first time that R. solani could intercept sheath papillae and employ them for attachment or penetration in two ways: (a) direct penetration by lobate or runner hyphae, appressorium and infection cushion and (b) indirect stomatal penetration. Assays using in vivo plant inoculation showed that disease lesion length was higher in the HS line than the MR line. Intraxylary hyphal colonization could be seen using microtomy to understand the cellular spatial dynamics of xylem colonization by R. solani. The penetration mechanism along with penetration hyphae of the R. solani inside HS rice lines describe in this paper for the first time using optical ultrastructure. These results supported for better understanding of host–pathogen interaction, penetration mechanism and colonization of R. solani in rice. [ABSTRACT FROM AUTHOR]

Being a model crop as well as a staple food crop, rice possesses a conspicuous position in plant sciences. Doubled haploid (DH) breeding in rice offers multiple advantages over conventional methods via accelerating the process of pure lines development. For ages, several methods have been devised for haploid production in rice. In vitro‐based methods have demonstrated their potential in DH production, but these methods are further impeded by stringent requirements and restricted to few species. Further, unlike maize, the in vivo DH breeding technology is still impractical in rice. Recent findings of the key molecular players behind the haploid induction (HI) trait in maize and rice have shown their potential in rice improvement programmes. In this review, we have discussed different strategies of HI in rice particularly focusing on recent progress made for developing haploid inducer stock (HIS) by employing both conventional and modern approaches. It also focuses on future implications of HIS so that it can be incorporated in the pipeline of modernized rice breeding. [ABSTRACT FROM AUTHOR]

Introgression Lines (ILs) carrying alien genomic segments in the homozygous state may or may not be able to contribute positively to the phenotype on account of replacement of cultivated genome segment, however, the genetic elite in heterozygous condition can be attributed to the presence of both recipient and donor genome complements. Therefore, overdominance or pseudo‐overdominance effect at the heterozygous loci is anticipated. Set of 318 ILs, carrying several genomic segments from "A" genome donor wild species, were used for developing test hybrids with CMS line PMS17A. Of these, three hybrids observed significant yield advantage (>25%) over recurrent parents and checks. Parental ILs of these hybrids viz., IL326, IL901 and IL951 carried 5.62%, 2.52% introgression from Oryza rufipogon and 6.71% from Oryza nivara, respectively. These ILs were also crossed with their recurrent parent to develop introgression line hybrids (ILHs) to observe the contribution of the alien segment(s), in the homozygous and heterozygous state. The traits studied have higher mean value when genomic segments from wild species were in the heterozygous state as compared to the homozygous state. [ABSTRACT FROM AUTHOR]

Considering the potentials of wild rice (Oryza spp.), as well as the need to enhance the yield potential of rice and to increase rice production to meet increasing demands, 1780 backcross inbred lines (BILs) were generated by crossing 70 accessions of six "AA" genome species: Oryza glaberrima Steud., Oryza barthii A. Chev., Oryza nivara Sharma & Shastry, Oryza rufpogon Griff., Oryza longistaminata A. Chev. & Roehr., and Oryza glumaepatula Steud. with two elite cultivars of Oryza sativa L. The wild species accessions were selected based on variation at the DNA markers and agromorphological traits. The BILs were generated by backcrossing F1s twice (thrice in some cases) to recipient parents, followed by continuous selfing and selection for the yield and yield component traits. The set of 1780 BC2F5 to BC2F10 BILs were evaluated in an augmented design over 3 yr. Based on ANOVA in augmented design, 108 agronomically superior BILs were selected and evaluated in randomized complete block design. Of the 108 BILs evaluated, 15 BILs showed >10% yield superiority over the recurrent parent, with spikelet per panicle and thousand-grain weight as most significant traits contributing to yield increase. Based on the contribution of donor accessions for the improvement of yield component traits, six accessions of O. glaberrima, one of O. barthii, two of O. nivara, two of O. rufpogon, and one each of O. longistaminata and O. glumaepatula were identified as potential donors that could be used more rigorously in transferring genes to cultivated rice. The BILs generated in the present study represents a reservoir of novel genetic variation. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION Yellow mosaic disease (YMD) is the most devastating disease of soybean under north Indian conditions. A recombinant inbred line population derived from SL 958 (R) × AGS 456 (S) was used to map the genes imparting YMD resistance. Genotyping by sequencing (GBS) of 148 individuals and the parents was used to identify polymorphic SNPs in the population. These were used to generate linkage maps and subsequently map the QTL.A QTL, MYMIV 1‐1.1, was mapped onto chromosome 6. The QTL was mapped at a genetic distance of 114.31 cM, with likelihood ratio of 81.34 (LOD 17.68), explaining 33.80% of the variation for the trait, with an additive effect of 1.22. MYMIV 1‐1.1 was flanked by SNPs Gm06_12614920 explaining 33.80% of variation and Gm06_12887789 explaining 31.04% of the variation. The QTL region spanned for a total of 2.798 Mbp.The QTL was mapped in an approximately 4 cM region. Flanking SNPs can be developed into linked markers for effective marker‐assisted selection. Out of the genes in the QTL region, Glyma.06G161700 (Suppressor of Gene Silencing/SGS3) is the strongest contender for the resistance gene. This is the first study documenting GBS‐based mapping of YMD resistance in soybean. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]