MicroRNA-mediated regulatory functions under abiotic stresses in legumes - Legumes Under Environmental Stress: Yield, Improvement and Adaptations - page 231

Chapter 14

MicroRNA-mediated regulatory functions
under abiotic stresses in legumes

Syed Sarfraz Hussain 1 , Mohammad Ali 2 and Bujun Shi 1
1 Australian Centre for Plant Functional Genomics (ACPFG), University of Adelaide, Glen Osmond, Australia
2 Institute of Biotechnology, Bahauddin Zakariya University, Multan, Pakistan

14.1 Introduction

Systematic research in legumes was initiated by the
selection of two model systems, Lotus japonicus (Handberg &
Stougaard, 1992) and Medicago truncatula (Barker
et al., 1990). Their genomes were sequenced (Sato et al.,
2008; Young et al., 2011) and made available to inter-
ested scientists for further exploitation in their research.
In parallel, significant progress was made in expression
profiling of legume genes (Lamblin et al., 2003; Oldroyd,
2005; Thompson et al., 2005). Besides, draft genomes
for pigeon pea (Varshney et al., 2012) and chickpea
(Varshney et al., 2013) have also become available to the
scientific community. In addition, significant scientific
efforts are underway in sequencing other important
legumes like peanut, pea and lentils ( http://www.
peanutbioscience.com /). Currently, global research
efforts involving molecular approaches to gain a deeper
knowledge of economically important legumes are in
progress, aimed at genetic improvement. As a part of
these efforts, de novo transcriptome assemblies were
developed in different legumes (Cheung et al., 2006;
Deschamps & Campbell, 2010; Garg et al., 2011;
Hiremath et al., 2011; Kupada et al., 2012). These
sequencing data will serve as a useful resource for
research on legumes at molecular and genomic levels.
Abiotic stresses including drought, salinity, extreme
temperatures and nutrient deficiency are major factors
contributing to reduction or total loss of crop production
(Hussain et al., 2011a). Extensive efforts have been
made to identify genetic elements involved in various
abiotic stresses in crop plants (Hussain et al., 2011a,b). It
has been widely reported that microRNAs (miRNAs)
are involved in the regulation of a wide variety of

Legumes belong to the Fabaceae/Leguminosae family,
with 20,000 species and representing the third largest
group of angiosperms. Legumes constitute the second
largest group of food and feed crops grown worldwide
(Iantecheva et al., 2013). Members of this family fill crit-
ical niches in most terrestrial biomes. Legumes stand
third behind cereals and oilseeds in global production
(Popelka et al., 2004) and account for 27% of primary
crop production in the world (Graham & Vance, 2003).
Annually, around 250 million tonnes of grain legumes
are produced worldwide, which represent major crops
used for food, feed and vegetable oil. A key contribution
of legumes to a sustainable environment is their ability
to fix atmospheric molecular nitrogen in symbiotic
association with rhizobia through a process called sym-
biotic nitrogen fixation (SNF) or root nodule symbiosis
(RNS) in most agricultural ecosystems (Urvardi &
Scheible, 2005). Legumes, known as 'green manure', fix
around 200 million tons of nitrogen (Graham & Vance
2003) in soil, thus reducing the need for chemical
nitrogen fertilizer. Therefore, legumes play a key role in
sustainable intensified agriculture, when used in
common farming practices as an intercrop in crop rota-
tion system by dramatically improving the organic
content of the field.
Certain unique features like nitrogen fixation, a pro-
tein-rich physiology and secondary metabolites make
legumes stand out from other crop plants; therefore, it
is extremely important to develop genomic tools in
legumes to understand their unique features (Cook, 1999).