Introgression of Drought Tolerance into Elite Basmati Rice Variety through Marker-Assisted Backcrossing

Drought is one of the major abiotic threat to rice production in the context of climate change.Super Basmati is an elite,fine grain basmati rice variety grown in Punjab,Pakistan.Due to drought sensitive in nature,its yield has been facing an alarming situation in production because of gradual decrease in irrigated water for a couple of years.Three reported novel QTLs for drought tolerance were selected for incorporation into Super Basmati by employing marker assisted selection strategy.IR55419-04 with novel QTLs was used as a donor parent.Foreground selection was performed by applying PCR based QTL linked SSR markers followed by recombinant selection by using 2-4 flanking markers.Background selection was exercised by using polymorphic SSR markers for maximum genome recovery of the Super Basmati.The individuals homozygous at the target QTLs and with maximum background of Super Basmati at the rest of the non-target genome was selected for evaluation of drought tolerance.Under drought stress conditions,the yields of all introgressed lines(ILs)were 44.2%-125.7%higher than recurrent parent.Six superior ILs that are drought tolerant and very similar to Super Basmati in terms of agronomic and grain quality traits are marked for release as drought-tolerant varieties in arid regions or for use in breeding programs of high grain quality and drought-tolerant parents.

QTL Analysis for Grain Iron and Zinc Concentrations in Two O. nivara Derived Backcross Populations

Identification of quantitative trait loci （QTLs） for grain mineral elements can assist in faster and more precise development of micronutrient dense rice varieties through marker-assisted breeding. In the present study, QTLs were mapped for Fe and Zn concentrations in two BC2F3 mapping populations derived from the crosses of O. sativa cv Swarna with two different accessions of O. nivara. In all, 10 and 8 QTLs were identified for grain Fe and Zn concentrations in population 1, and 7 and 5 QTLs were identified in population 2, respectively. Eighty percent of the QTLs detected in both populations were derived from O. nivara. Five QTLs for Fe and three QTLs for Zn explained more than 15% phenotypic variance either in interval or composite interval mapping. The locations of O. nivara derived QTLs such as qFe2.1, qFe3.1, qFe8.2 and qZn12.1 were consistently identified in both the populations. Epistatic interaction was observed only between RM106 and RM6 on chromosome 2 and between RM22 and RM7 on chromosome 3 for Fe concentration in population 1. Sixteen candidate genes for metal homeostasis were found to co-locate with 10 QTLs for Fe and Zn concentrations in both the populations. Most of the Fe and Zn QTLs were found to co-locate with QTLs for grain yield and grain quality traits. Some of the major effect QTLs identified can be used to improve rice grain Fe and Zn concentrations.

Advances in Studies of Genetic Improvement of Sugarcane

Sugarcane(Saccharum spp.) is a large perennial herbaceous plant that is cultivated in tropical and subtropical regions of the world,and it is also one of the most efficient crops in the world in converting energy from sunlight into chemical energy. As an essential sugar crop and energy crop,sugarcane is receiving an increasing concern for its variety improvement. Traditional breeding and cultivation techniques have contributed a lot to increasing sugarcane yield and sucrose content. In recent years,development and application of biotechnology provide much help for genetic improvement of sugarcane. For convenience of breeders fully knowing advances in studies of sugarcane genetic improvement,this paper elaborated conventional breeding,genomics,GM technology,and molecular marker assisted breeding.