Molecular and physiological responses of recalcitrant indica rice to lignosulfonates during callus regeneration
Lignosulfonate (LS) is commonly used as an enhancer to promote plant growth. The recalcitrant Oryza sativa indica cv. MR219 rice is an important local high yield rice cultivar that is widely cultivated in Malaysia. However, low callus regeneration rate of MR219 hinders further exploitation in...
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| Format: | Thesis |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/75618/1/FBSB%202018%2031%20IR.pdf |
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| Summary: | Lignosulfonate (LS) is commonly used as an enhancer to promote plant growth. The
recalcitrant Oryza sativa indica cv. MR219 rice is an important local high yield rice
cultivar that is widely cultivated in Malaysia. However, low callus regeneration rate of
MR219 hinders further exploitation in cultivar improvement. Hence, LS was introduced
in the culture medium in effort to enhance in vitro cultivation of MR219. To date, the
effects of LS on regeneration of MR219 has not been reported. Therefore, this study was
undertaken to evaluate the effects of LS on callus proliferation, shoot induction and
shoot growth of MR219. The MR219 calli were proliferated on MS supplemented with
different types (aNaLS and aCaLS) and concentrations (50, 100, 150, 200 mg/L) of LS.
The optimum callus proliferation rate (88%) was obtained in week 3 on MS
supplemented with 100 mg/L aCaLS in the presence of plant hormone. However, both
LSs did not enhance the shoot induction efficiency whereby 50% of the shoot induced
was albino in MS fortified with 100 mg/L CaLS. In shoot growth study, shoot apices
were cultured in MS supplemented with different types (aNaLS and aCaLS) and
concentrations (100, 200, 300 and 400 mg/L) of LS. The optimum shoot growth was
observed in MS supplemented with 300 mg/L aNaLS that is taller by 26% of control
height. To understand the growth promoting effects of LS, aCaLS treated callus was
used as a study model. Results showed that aCaLS increased callus proliferation rate by
67% and adventitious root formation by 62% in MS without hormone. Hence, it was
shown that the LS effect was found to be independent of hormone. Under scanning
electron microscopy, adventitious roots were seen protruding out from aCaLS-treated
calli. Further expression analysis of adventitious root-related genes (OsWOX11,
OsAUX1 and OsIAA23) on treated calli, OsWOX11 expression recorded 1.7-fold
expression increment, implying a positive role of aCaLS in adventitious root
development. In addition, aCaLS-treated calli recorded 1.2-fold higher endogenous
indole-3-acetic acid (IAA) content and increment of nutrient ions (Na, K, Ca, Mg, Fe,
Mn, Zn and Cu) uptake. Consistently, expression analysis of auxin-related genes
(OsASA1, OsTAA1 and OsYUC1) and nutrient uptake-related genes (OsAKT1, OsHAK5,
OsCBL, OsCIPK23 and OsCamk1) also showed a similar increment trend. The Ca increment was observed throughout four weeks but the major increment of K was only
detected starting from week two. The observed rise of Ca following the enhancement of
endogenous K content suggested the possible cross-talk between these ions uptake. The
LC-MS/MS analysis suggested that there was an increased in carbon and nitrogen
metabolisms in aCaLS treated callus. Taken together, the presence of aCaLS improved
MR219 callus proliferation, up-regulated endogenous auxin synthesis, nutrients uptake
and carbon-nitrogen metabolisms that ultimately contributed to calli growth
enhancement. The findings of this study would be useful on improving the in vitro
cultivation of the recalcitrant rice cultivars. |
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