The different responses of rice genotypes to heat stress associated with morphological, chlorophyll and yield characteristics

Sixteen rice genotypes were planted under normal and high temperature during 2018 and 2019 seasons to understand the mechanisms that make plants tolerant or susceptible to heat stress and methods which may lead to generate new varieties with sustainable yield production. The combined analysis showed significant differences at the level of probability 0.05 and 0.01 among years for all characters except, chlorophyll content and leaf rolling which would indicate wide differences among the weather of both years. Environment’s variance was significant at the level of probability 0.01 over all characteristics. The significant differences at the level of probability 0.01 were recorded among genotypes and G x E interaction variances for all characteristics. The highest values of panicles number plant-1 were obtained from ‘Giza 178’ and ‘Hybrid 2’, however, the highest values of 100-grain weight were recorded with ‘Giza 179’ and ‘Egyptian Yasmine’. The minimum values of sterility% were recorded with ‘Sakha 107’ and ‘IET1444’. Concerning the cultivars performance across two environments, the cultivars ‘Giza 178’, ‘Giza 179’, ‘Sakha 107’ and ‘IET 1444’ gave the best desirable values over natural and heat stress so, those cultivars are considered to play a vital role in breeding program to enhance heat stresses tolerance accompanied with high yield potential.

[IN1329] Fig Psyllid Homotoma ficus (L.) (Insecta: Hemiptera: Homotomidae); Curtain Fig Psyllid Macrohomotoma gladiata Kuwayama (Insecta: Hemiptera: Homotomidae); and Ficus Leaf-Rolling Psyllid Trioza brevigenae Mathur (Insecta: Hemiptera: Triozidae)

This article details three adventive (to North America) psyllid species that feed on ficus. Homotoma ficus (the fig psylla) was noticed first in 1969, and Macrohomotoma gladiata (the curtain fig psyllid) and Trioza brevigenae (the ficus leaf rolling psyllid) were found to be present in 2015 and 2016, respectively. All three three species are currently found only in California, but could possibly spread to other states including Florida in the future.

Breeding for Drought Resistance

Drought is the most severe abiotic stresses in many parts of the world and is one of the major problems in present-day climatic scenario. Drought tolerant varieties are with high demand which seems to be a great challenging task to plant breeders however difficulties are combined by the difficulty of crop yield on the genetic and physiological bases. Drought resistance may be defined as the mechanism(s) causing minimum loss of the yield in a drought environment relative to the maximum yield in a constant-free of optimal environment for the crop. Several researchers explained the plant reaction to drought through drought escape, dehydration avoidance, and/or dehydration tolerance mechanisms. Drought stress decreases size of the leaves, stem extension and root proliferation inside the soil, it also disturbs plant water relations and reduces water-use efficiency ultimately reduces the yielding ability of the plant so, breeding for Drought resistance is a good approach, following different breeding strategies and approaches to develop a drought resistant variety combining both conventional and molecular approaches. Considering the parameters like root morphology studies, proline estimation, leaf rolling etc., Selection based on a comprehensive approach of testing might be more effective in breeding better drought-tolerant cultivars.

Major QTLs, qARO1 and qARO9, Additively Regulate Adaxial Leaf Rolling in Rice

Moderate leaf rolling is considered optimal for the ideal plant type in rice (Oryza sativa L.), as it improves photosynthetic efficiency and, consequently, grain yield. Determining the genetic basis of leaf rolling via the identification of quantitative trait loci (QTLs) could facilitate the development of high-yielding varieties. In this study, we identified three stable rice QTLs, qARO1, qARO5, and qARO9, which control adaxial leaf rolling in a recombinant inbred line (RIL) population derived from a cross between Tong 88-7 (T887) and Milyang 23 (M23), using high-density SNP markers. These QTLs controlled the rolling phenotype of both the flag leaf (FL) and secondary leaf (SL), and different allelic combinations of these QTLs led to a wide variation in the degree of leaf rolling. Additive gene actions of qARO1 and qARO9 on leaf rolling were observed in a backcross population. In addition, qARO1 (markers: 01id4854718 and 01asp4916781) and qARO9 (markers: 09id19650402 and 09id19740436) were successfully fine-mapped to approximately 60- and 90-kb intervals on chromosomes 1 and 9, respectively. Histological analysis of near-isogenic lines (NILs) revealed that qARO1 influences leaf thickness across the small vein, and qARO9 affects leaf thickness in the entire leaf and bulliform cell area, thus leading to adaxial leaf rolling. The results of this study advance our understanding of the genetic and molecular bases of adaxial leaf rolling, and this information can be used for the development of rice varieties with the ideal plant type.

Studies of Raspy Crickets: Magnumtergalis n. gen. a new gryllacrid genus with elongate male terminalia (Orthoptera: Gryllacrididae) from Colombia

Magnumtergalis n. gen. a new genus from the Inter-Andean Valleys and midlands of the Colombian Andes’ central cordillera is described. Two very peculiar species are placed within this genus, M. aldarioarenasi n. sp. (type species) and M. albonigra n. comb. An unusual terminalia to the family Gryllacrididae characterizes this genus, in which the ninth tergite is noticeably prolonged, covering the other structures of the male terminalia. This is the first genus of leaf-rolling crickets described from the Neotropics in the last 80 years.

Heritability Paterns of Some Agro-Botanical Characters Related to Yield and Drought Tolerance in Two Landraces of Rice

Two landraces of rice, AWGUII-04 and IJ-124, were characterised and assessed for phenotypic variability, heritability, genetic advance and modes of inheritance of some primary yield and drought-tolerance traits. The target traits for yield were a percentage of filled spikelets, plant form, tillering, and for drought tolerance, leaf rolling, ratooning and maturity. This study was carried out to help both breeders and farmers make a wise choice when carrying out hybridisation and on the field. Hybridisation produced three F1 hybrids that were advanced to F2 generation. Quantitative and qualitative vegetative and reproductive data were taken from each F2 population. The results obtained showed high heritability (62–100%) in all the thirty-eight vegetative and reproductive traits. The genetic advance was high (> 20%) in all the target traits except for leaf rolling. The traits segregated in the following ratio: plant growth form – 9:6:1; the percentage of filled spikelets – 13:3; ratooning – 3:1; maturity – 15:1; the number of tillers – 15:1 and leaf rolling – 15:1. The high heritability of the above traits makes them highly dependable for rice crop improvement.

Bioinformatics studies on structures, functions and diversifications of rolling leaf related genes in rice (Oryza sativa L.)

Leaf morphology of crop plants has significant value in agronomy. Leaf rolling in rice plays a vital role to increase grain yield. However, collective information on the rolling leaf (RL) genes reported to date and different comparative bioinformatics studies of their sequences are still incomplete. This bioinformatics study was designed to investigate structures, functions and diversifications of the RL related genes reported till now through several studies. We performed different comparative and functional analyses of the selected 42 RL genes among 103 RL genes using different bioinformatics techniques including gene structure, conserved domain, phylogenetic, gene ontology (GO), transcription factor (TF), Kyoto Encyclopedia of Genes and Genomes (KEGG) and protein–protein network. Exon-intron organization and conserved domain analysis showed diversity in structures and conserved domains of RL genes. Phylogenetic analysis classified the proteins into five major groups. GO and TF analyses revealed that regulation-related genes were remarkably enriched in biological process and 10 different TF families were involved in rice leaf rolling. KEGG analysis demonstrated that 14 RL genes were involved in the KEGG pathways, among which 50% were involved in the metabolism pathways. Of the selected RL proteins, 55% proteins were non-interacting with other RL proteins and OsRL9 was the most interacting RL protein. These results provide important information regarding structures, conserved domains, phylogenetic revolution, protein–protein interactions and other genetic bases of RL genes which might be helpful to the researchers for functional analysis of new candidate RL genes to explore their characteristics and molecular mechanisms for high yield rice breeding.

QTL detection and putative candidate gene prediction for leaf rolling under moisture stress condition in wheat

Leaf rolling is an important mechanism to mitigate the effects of moisture stress in several plant species. In the present study, a set of 92 wheat recombinant inbred lines derived from the cross between NI5439 × HD2012 were used to identify QTLs associated with leaf rolling under moisture stress condition. Linkage map was constructed using Axiom 35 K Breeder’s SNP Array and microsatellite (SSR) markers. A linkage map with 3661 markers comprising 3589 SNP and 72 SSR markers spanning 22,275.01 cM in length across 21 wheat chromosomes was constructed. QTL analysis for leaf rolling trait under moisture stress condition revealed 12 QTLs on chromosomes 1B, 2A, 2B, 2D, 3A, 4A, 4B, 5D, and 6B. A stable QTL Qlr.nhv-5D.2 was identified on 5D chromosome flanked by SNP marker interval AX-94892575–AX-95124447 (5D:338665301–5D:410952987). Genetic and physical map integration in the confidence intervals of Qlr.nhv-5D.2 revealed 14 putative candidate genes for drought tolerance which was narrowed down to six genes based on in-silico analysis. Comparative study of leaf rolling genes in rice viz., NRL1, OsZHD1, Roc5, and OsHB3 on wheat genome revealed five genes on chromosome 5D. Out of the identified genes, TraesCS5D02G253100 falls exactly in the QTL Qlr.nhv-5D.2 interval and showed 96.9% identity with OsZHD1. Two genes similar to OsHB3 viz. TraesCS5D02G052300 and TraesCS5D02G385300 exhibiting 85.6% and 91.8% identity; one gene TraesCS5D02G320600 having 83.9% identity with Roc5 gene; and one gene TraesCS5D02G102600 showing 100% identity with NRL1 gene were also identified, however, these genes are located outside Qlr.nhv-5D.2 interval. Hence, TraesCS5D02G253100 could be the best potential candidate gene for leaf rolling and can be utilized for improving drought tolerance in wheat.