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Genetically Modified Rice Could Actually Grow in Martian Regolith, New Study Suggests
One of the biggest challenges to growing food on Mars is the presence of perchlorate salts, which have been detected in the Martian regolith (soil) and are generally considered to be toxic for plants.
Gann et al. show that in principle it is possible to grow rice plants in MMS1 but levels of (Mg(ClO4)2) can be critical to both germination and growth; moreover, they presented that editing SnRK1a could potentially provide an approach to develop as table rice line that can germinate and grow in MMS1 with (Mg(ClO4)2).
“In-Situ Resource Utilization will become increasingly important as human space exploration progresses,” said Peter James Icalia Gann from the University of Arkansas and his colleagues.
“Resupply missions can be expensive, so we need practical and affordable ways to use resources on other planetary bodies.”
Gann and co-authors were able to simulate Martian soil using basaltic rich soil mined from the Mojave Desert, called the Mojave Mars Simulant 1 (MMS1), which was developed by scientists from NASA.
They then grew three varieties of rice, including one wild-type and two gene-edited lines with genetic mutations that better enable them to respond to stress, such as drought, sugar starvation or salinity.
These varieties were grown in MMS1, as well as a regular potted mix and a hybrid of the two.
While plants were able to grow in the Martian simulant, they were not as developed as those grown in the potting soil and hybrid mix.
Replacing just a quarter of the Martian simulant with potting soil resulted in improved development.
The researchers also experimented with the amount of perchlorate in the soil, finding that 3 grams per kilogram was the threshold beyond which nothing would grow, while mutant strains could still root in 1 gram per kilogram.
Their findings suggest that there might be a way forward for genetically modified rice to find purchase in Martian soil.
The team’s next steps will include experimenting with a newer Martian soil simulant called the Mars Global Simulant, as well as other rice strains that have increased tolerance for higher salt concentrations.
An important part of the research will be determining to what degree perchlorate may be leeching into the plant from the soil.
Farther down the road, the scientists would like to introduce rice into a closed habitat chamber and place it in a Mars simulation chamber that replicates the temperature and atmosphere of the planet.
“Whether humans ever colonize Mars, our research could have applications here on Earth,” said Dr. Abhilash Ramachandran, a researcher at the Arkansas Center for Space and Planetary Sciences.
“I spoke with an Australian researcher from an area where the soil had high salinity, and saw their work as a potential way to grow food there.”
“We could use Earth as a terrestrial analog before the seeds ever get sent to Mars.”
注释：
perchlorate: n
表示" [化]高氯酸盐"，means "a salt of perchloric acid"，如：nly the perchlorate shows marked sensitiveness and possibly initiating properties.只有高氯酸盐表现有显著的感度和可能具有起爆性能。
regolith: n
表示" 表皮土；风化层", 如：Solar arrays are set up on the regolith that covers the Moon’s surface. 太阳能电池方阵覆盖着月球表土。
Germination: n
表示" 发芽；萌芽；"，means "the process whereby seeds or spores sprout and begin to grow"，如：Temperature is most important for seed germination. 温度对种子的发芽至关重要。
mutation: n
表示"突变"，means "(biology) an organism that has characteristics resulting from chromosomal alteration"，如：Most of these mutations are harmless. 大部分的基因突变是没有害处的。
salinity: n
表示" 盐浓度；盐分"，means "the relative proportion of salt in a solution"，如：For water of photograph comparing hot spring, the salinity content of natural mineral water is more. 相比温泉水来说，天然矿泉水的盐分含量较多。
simulant: adj
表示"拟态的； 看起来像 ... 的"，means ""，如：It is shown that artificial neural network is effective to study the simulant formability of the sheet metal. 本文的研究方法和结果表明，人工神经网络是研究板料的模拟成形性的一条有效途径。
leech: v
1. v表示" 以水蛭吸血"，means "draw blood"，如：He was the only person whom she could leech on to. 他是她惟一可依赖的人。
2. n表示"水蛭"，means "carnivorous or bloodsucking aquatic or terrestrial worms typically having a sucker at each end"，如：A leech is a small blood-sucking worm and usually lives in water.水蛭是一种小型吸血虫，通常生活在水中。
中文简要说明：
我们可在未来10年，看到人类登陆火星，甚至移民火星。那么他们该吃什么? 种田吧！然而，先前的调查发现，火星土壤有高氯酸盐，这对多数植物有毒。所幸，科学家已经利用基因改的方式，培养出能在火星生长的水稻。
美国阿肯色州大学的冈恩博士(Peter James Icalia Gann)领导的研究团队，完成火星稻种的开发。他说：「随着人类太空探索的进展，善用外星球资源，将变得越来越重要。因为从地球运送补给物资是极端的昂贵，最好能够就地取材，就地生活。」
「虽然火星看起是不毛之地，但对我们科学家来，至少上面有水、风化层的土壤、阳光，以及二氧化碳，这已经算丰富了，我们可以再加一些火星欠缺的东西。」
冈恩与研究团队分析火星土壤的成份，然后着手制作符合火星特征的土壤。他们认为美国莫哈韦沙漠(Mojave Desert)的砂土最接近火星土壤，称为莫哈韦沙漠-火星模拟物 1号 (MMS1)，它是由美国航天总署的科学家开发的。
然后，他们种植了三种水稻品种，包括一种野生型，和两种基因改造型，基因突变使它们能够更好地应对干旱、缺养料与高盐度这种恶劣环境。
研究人员还对土壤中高氯酸盐的含量进行了实验，发现每公斤3克，是多数植物的最高耐受力，但是有一种突变株可在每公斤 1 克的高氯酸盐环境仍能生根。显然基改水稻，可能在火星土壤中生存。
该团队的下一步实验，是要挑战其他的火星土壤，最近有一种称为「火星全球模拟」的新型火星土壤刚刚推出，是依照最新的火星地质分析资料而制作的。该研究的最重要部分，是要确定高氯酸盐从土壤中渗入植物的程度。
完成下一阶段后，科学家们还希望将火星基改稻子送到封闭的模拟室里，将其调整成火星温度和大气环境，以及辐射值，看看它们的耐受力。
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