Stay Green Trait: A Potentiality in Plant Breeding

 

 

 Plant breeding has made great progress in supplying food to the growing human population

through the release of more efficient cultivars which are resilient to varying environment. In current

agricultural scenario, the genotypes with high productive efficiency can often be availed through

insighting into physiological facets and stress adaptive strategies of crops.3

One of such traits is ‘stay green’. It is differentiated as a variant in which senescence is delayed

in comparison to cultivated genotypes. This trait has been considered as an important component in the

genetic improvement of several crops to promote drought tolerance along with the improvement in the

fodder and keeping quality. Five distinct stay-green plant types have been reported based on chlorophyll

degradation and rate of senescence where the occurrence of various physiological and genetic

modifications have been detected. Naturally, the combination of two or more stay green types are often

observed.3 In contrast, senescence is a physiological process characterised by mobilization of nutrient

reserves and cytokinins into fruits and seeds. Understanding of the physiological aspects, molecular

mechanisms and hormonal pathways related to the stay-green trait under heat stress would aid in breeding

for productivity.1

Mutations can also create stay green variants for the drought combat. In Rice, an alkalyting

agent N-methyl-N-nitrosourea was employed to isolate stay green mutant from the glutinous japonica

rice Hwacheong-wx. Phenotypically, leaves of this mutant remained green while that of wild types

senesced. The stay green phenotype was reported to be controlled by a single recessive nuclear gene sgr,

which was mapped to the long arm of chromosome 9.2 A stay-green mutant line NF2089 identified in

Medicago truncatula population with MtSGR gene, regulated by the insertion of Tnt1(TE) which retained

green leaves, mature pods during senescence. A transgenic alfalfa (Medicago sativa) line has been

developed by transferring SGR gene (MsSGR) that offered the opportunity to produce premium hay.4

To battle against moisture stress, there is a need to explore stay greens in a number of crops for

elevating yield under stress conditions. Conventional and non-conventional methods aid this breeding in

the climate change scenario for catering the world in terms of cereals, pulses, green vegetables, cut

flowers, ornamentals, and forages. The use of stay-green character in breeding programs may result in

remarkable gains bagging higher yield, industrial quality, and tolerance to abiotic stresses.2

Reference:

1. ABDELRAHMAN, M., EL-SAYED, M., JOGAIAH, S., BURRITT, D. J. AND TRAN, L. P., 2017, The “staygreen”

trait and phytohormone signalling networks in plants under heat stress. Plant Cell

Reports, 36 (7): 1009–1025

2.ICHA, K.W., LEE, Y.J., KOH, H.J., LEE, B.M., NAM, Y.W., AND PAEK, N.C., 2002, Isolation,

characterization, and mapping of the stay green mutant in rice. Theor. Appl. Genet., 104(4): 526–

532

3. LUCHE, H. D. S., SILVA, J. A. G., MAIA, L. C. M. AND OLIVERIA, A. C., 2015, Stay-green: a potentiality

in plant breeding. Crop production, 45 (10): 1755-1760

4. ZHOU, C., HAN, L., PISLARIU, C., NAKASHIMA, J., FU, C., JIANG, Q., QUAN, L., BLANCAFLOR, E. B., et

al., 2011, From model to crop: Functional analysis of a STAY-GREEN gene in the model

legume Medicago truncatula and effective use of the gene for alfalfa improvement. Plant

Physiol., 157: 1483–1496