Yesterday we had a break from the field work. It was still a pretty busy day. Working days at CIP start early and both Philippe and I wanted to have a look in the labs and see some of the first results.

After breakfast we started with a seminar, Jean Ristaino talked about her work on global P. infestans diversity, which was very interesting. After the seminar, I could have a quick look in the lab, where two of the technicians could show me the plates with the results from our first day collecting. One of the reasons for this trip was to figure out what the best sampling methods are. We can take the infected leaves and put them in a petri dish with some water agar to keep them humid, so that they don’t dry out, but carrying loads of plates is not easy and in the lab, you can get any kind of growth on these plates, the pathogen that you want, but also opportunists that make it harder to isolate the real infecting pathogen Moreover, plates get contaminated when not store properly and I had already thrown away some plates the previous days. Alternative methods include using sliced potatoes. You can store leaves in between two slices and keep it for a few days. The idea is that the potato then gets infected and that after you are back in the lab you can grow Phytophthora on the potato and isolate it later. This is supposed to be cleaner and the potatoes are easier to carry and obtain, but we don’t know if it works with at all Phytophthora strains that grow on wild tomatoes. They might not be adapted to growing on a potato. Another issue might be being away from a temperature controlled lab for 3 days. That might stress the sample so that we cannot recover anything. Unfortunately, both methods take mostly more than 5 days to get proper results. So, so far we have only one P. infestans sample that has already been processed further. That means, the spores of P. infestans had grown, were washed off and reinoculated on fresh, susceptible potato and tomato leaves. The cool thing is, it came from the first plant collected on the first day. Besides that there are a large number of promising candidates from the first three days, but also a back-log of samples that we brought in yesterday. Manpower is limited, but we can store the samples in a cold place for a while and process after the weekend and a lot of boxes with sliced up potatoes are already prepared and filling the lab.

At 11, I had a meeting with Tiina Sarkinen. She is an expert on wild Solanum species, including tomato, and it was really interesting to hear her thoughts and to share experiences.  Of course, I already knew that there are a lot of interesting wild solanum species, but that there were that many. There is definitely room for a lot more research in this area.

For lunch we went to a nice little restaurant on the campus of the nearby national agricultural university La Molina. I don’t say it often, but the portion was way too big. Very tasty though. Anticuchos served with typical Peruvian potato and maize varieties. Tiina had recommended me to take a little walk on the campus after lunch. I’d find some nice things there, and she was right. Next to some of the trial fields, there was a good population of S. pimpinellifolium. Some were clearly suffering from one thing or the other, but other looked beautifully healthy. I collected three specimens of which one is almost certainly infected with Phytophthora. Now that is easy sampling.

Philippe has spend part of the day in the lab looking at his own samples. For him this trip is not so much about how to sample and process Ralstonia, he’s been doing it for years. For him it is the question whether there is Ralstonia at all in these environments and in these species. If there is, that might explain more about the evolution of the species. Also he is not alone in the lab.

When I returned at the CIP, we had to pack our stuff for the next week. Double checking if we still have all that we needed. From pens to plastic bags, but also letters that explain what we do, so that we don’t get in trouble with the police. We had to hand back the truck we rented and sort the paperwork for the car rental and all other things we do next week. As one would expect, these things take forever, so by the time this was all done, we had to get ready to go for dinner. Dinner was at a house warming party of some people working at CIP. We felt very welcome in the CIP family and it was very nice to talk to all people there and to hear about the different research going at the institute.

Today, I will make the planning for the rest of the stay here and I also hope to have a quick look in the lab in the morning, if someone can let me in. The afternoon will be used to work away all unanswered emails and other things from the past few days. Late afternoon we fly to Arequipa for the last leg of this trip. I am really looking forward to that. This is the area where S. peruvianum and S. chilense grow. S. chilense are the plants that I have worked with in Freising for the last 2 years.
I must also say, it is very exciting and rewarding to do this work, but also really tiring. So, before we hit the road on Monday again, we will use the Sunday to relax in Arequipa and be tourist for one day!